That is: "why isn't the United Nations all over this like a rash?"

Trump's actions should have come as no surprise. It is now almost three years since he was elected on the back of a pledge to bring American troops home from "endless wars" in the Middle East, including this one.

He has flagged his intention to pull back ahead of the 2020 elections on numerous occasions since then; a fact acknowledged by Kurdish commander in chief, Mazloum Abdi, in a weekend opinion piece on ForeignPolicy.com.

"President Donald Trump has been promising for a long time to withdraw US troops," he wrote. "We understand and sympathise. Fathers want to see their children laughing on their laps, lovers want to hear the voices of their partners whispering to them, everyone wants to go back to their homes."

Abdi used the same article to warn that if the Kurds had to choose between falling victim to a Turkish genocide or doing a deal with Russia and Syria they would do whatever it took to save their people.

"In light of the invasion by Turkey and the existential threat its attack poses for our people, we may have to reconsider our alliances. The Russians and the Syrian regime have made proposals that could save the lives of millions of people who live under our protection. We do not trust their promises. To be honest, it is hard to know whom to trust."

Overtaken by the speed with which events have moved, the Kurdish leaders have had to overlook those misgivings and come to an agreement with Bashar al Assad and Vladimir Putin.

It was, given the absence of any other offers of practical assistance, the only option they had left. It has, unfortunately, made an already potentially cataclysmic situation even worse.

In addition to opening the gate to the possible re-establishment of Islamic State in the region, the deals mean it may only be a matter of time before Russia is engaged in a proxy war with Turkey, a NATO member for almost 70 years, that would be fought with Syrian and Kurdish troops.

Given the international nature of the conflict and the risk of further escalation one would have thought the UN would have stepped in by now. Surely there must be a strong case for the establishment of an international peacekeeping force.

The trouble is that just isn't going to happen. When the Security Council met to draft a response to the Turkish invasion last week its members weren't even able to agree on the wording for a motion to censure the attacks.

A call made by the members of the Arab League ahead of the weekend for the Security Council to take meaningful action has, to date, elicited no meaningful response.

All we have seen from the UN to date is an attempt to tabulate the numbers of dead, wounded and displaced along with hand-wringing and hot air.

Speaking to journalists in Copenhagen, UN Secretary-General Antonio Guterres said a de-escalation of the crisis was "absolutely essential". He also said he did not "believe in military solutions to the Syrian problem" and stressed the need for a "political solution".

Unfortunately he seems to be either unwilling or unable to contribute to either of these outcomes.